The Boulogne Bicycle Rally occurs annually in May with the chance meeting of cyclists in Boulogne. By small miracle they cycle the same route at the same time. It takes part on the approximate route of the historic Boulogne Grand Prix circuit with many people having completed it on vintage bicycles. There are refreshment stops along the way. It happens every year on the second bank holiday weekend in May and follows a traditional schedule that never really varies from what happened last year.
If you choose to cycle in Boulogne and would like to increase the chances of meeting people you could arrive on Saturday evening and look up the Vole Hole bar. There are eateries available locally. For the cycle you'd find the best time to leave is at 10am Sunday from the central court yard of Château de Boulogne-sur-Mer. The map below shows the approximate route of the cycling and some known refreshment stops along the way. The map below that shows the actual route of the Boulogne Grand Prix in 1909.
This was the route documented in l'Auto for the 1909 Grand Prix. From the text below it the route had been run four times before, so perhaps the cycling route is more faithful to the original circuit. Perhaps not.
The long straight from La Capelle is now the N42 dual carriageway so that is why it is missed out. Alincthun has all the letters of lunch in its name, so is a great place for your lunch.